Cement composition with additive to reduce water loss from a slurry thereof



Patented Aug. 11, 1953 CEMENT COMPOSITIONWITH ADDITIVE TO 088 FROM SLURRY REDUCE WATER L THEREOF Matthew J. BorisIEast Chicago, Ind., and Norman 0. Ludwig, Chicago, 111., assignors to Universal Atlas Cement Company, a corporation of Indiana No Drawing. Application January 24, 1951, Serial No. 207,664

This invention relates to a cement composition slurries of which exhibit a low water loss, and

are therefore particularly adapted for cementing oil wells.

6 Claims. (Cl. 260-29.6)

the amount of PVA used. Generally, from .02 to .30% by weight of cement may be used although from .06 to 24% is usually to be preferred. With such addition of a boric acid or an alkali salt thereof to a cement mix includ- The rapid loss of water from a slurry of ordinary Portland cement, when placed against a ing PVA and a defoaming agent, the amount of porous formation, is a serious handicap in well- PVA may be kept below 1% without impairing the cementing operations. It prevents the slurry Water-retention property. With this reduction from penetrating the formation as deeply as dein the amount of PVA, less defoaming agent is sired and causes excessive back pressures to build 10 needed and a double economy is thereby effected. up in the casing through which the slurry is The results of tests performed on slurry samples pumped. A modified cement composition yieldmade from our improved composition, as set ing slurries with a low water loss is disclosed forth in detail herebelow, will indicate sufficientin an application of Norman C. Ludwig, erial ly the preferred composition. In all the tests No. 704,295, filed October 18, 1946, now Patent listed, ASTM Type II Portland cement was used, No. 2,576,955, for Low-Water-Loss Cement. a typical analysis thereof being as follows:

Oxide Analysis Percent) Wagner Cement ttiitt w sio. A120: FezO: CaO MgO MnO S03 ASTM TypeII 22.2 5.0 4.2 64.1 1.0 0.16 1.8 0. 94 1,870

That composition is Portland cement with addi- All slurries were made by mixing in a mechanitions of from .025 to 5% of polyvinyl alcohol and cal mixer 100 parts cement with 60 parts water from .02 to 05% of a defoaming agent, both by by weight after blending the dry additives (PVA weight of cement. Insuch composition the polyand borax) with the cement. The defoaming vinyl alcohol (PVA) imparts the desired low waagent (tributyl phosphate) was added to the ter-loss characteristic and the defoaming agent water in the amount of .015 to .12% by weight minimizes the foam-stabilizing property of the of cement. The water-loss tests were made with polyvinyl alcohol. a Baroid Wall-building Tester in accordance Both the additives used in the modified comwith the method given in the API Code No. 29, position referred to above increase the cost of Standard Field Procedure for Testing Drilling the cement to the user and this naturally restricts Fluids. The cement slurry was mixed with a the sale thereof despite the desirable properties Kitchen Aid, Model K 4-B mixer equipped with achieved by the additives. We have discovered a wire whip beater and operated at the No. 4 that the addition of a further modifying agent pe d control- The m x n w continued for to said composition materially reduces the ten minutes for the room temperature tests. For amount of PVA needed to produce a given waterthe 150 F. tests, the slurry was mixed one minretention characteristic. The cost of our addiute at room temperature and then transferred tional modifier is negligible and it accordingly into a metal mixing cell which fits into a water permits low-water-loss cement to be made at a bath controlled at 150 F. and the mix n was considerably lower cost than heretofore possicontinued for ten minutes. For the high-temble. perature tests, the wall-building tester was pre- Our invention, stated briefly, is a cement comheated to 150 F. with a circular electric heatposition having from .1 to 1% or 2% PVA added ing coil. to reduce water loss, a small amount of a'de- Table I below gives specific examples of the foaming agent to minimize foam stabilization, invention showing the effect of borax (sodium and a third addition agent which increases the tetraborate) on the water-loss of slurries conefiectiveness of PVA as a water-retention agent. sisting of 100 parts ASTM Type II cement, 60 'I'histhird addition agent is boric acid (i. e., orthoparts water, 0.125 to 1.0 parts PVA and .015 to boric, meta-boric or tetra-boric) or alkali salts .12% tributyl phosphate (defoaming agent) both thereof. Sodium tetraborate, commonly known by weight of cement. In these examples, modias borax is the preferred salt but others may be fied starch (thin-boiling starch or dextrin) was used as well as the Y acids themselves. The amount. of the third modifying agent varies with used as a retarder, in accordance with known procedure.

TABLE I Composition:

ASTM Type-11 Cement+60% Water Borax, PVA and Starch, Percent by Weight of Cement Water-Loss, No. 50 Paper 'Tri'butyl Test Borax, PVA, gg Phos Room F No. Percent Percent Starch phate, Temperature mL/sack V 'mfi. min. In]. min..

None None None None 204 1 1. 75 196. 5 1 0. 75' None 1. 0. 07 50 8 30 39 30 0. 02 1. 0 0. 07 50 8 30 26 30 0. 06 1.0 0.07 50 '5. 30 1 11.5 30- 0.12 1. 0 0. 07 50 4. 5 30- 1 7, 3e 0. l8 1. 0 0.07 50 5. 5 30 9 30 0. 24 1. 0 0. 07 50 7 5 30 1-5 30' 0.30 1.0 0.07 50 8- 30 50.5 30 0. 36 1. 0 0. 07 50 163 1 1. 08 0. 42 1.0 0.07 50 171 1 0.83 None 0'. 5 0. 07 25 17. 5 30 102 30'. 0.02 O. 5 0. 07 25 30 63. 5 30 0. 06 0; 5 0. 07 14 29 30' 0. 09 0. 5 0.07 25 10 30 21 3.0 0.12 0. 5 0.07 25 8. 5 30 22 30 0.15 0.5 0.07 25 8 30 17. 5 30 0.18 0. 5 0. 07 25 12. 5v .30 31 30 0. 24 0. 5 0. 07 25 14. 5 30 81 30 0.30 0. 5 0.07 25 16. 0 30 185 0.75 None 0. 25' 0. 07 12. 5 29; '5 30 173 30 0. 02 0; 25 0. 07 12. 5 26 30 30 0. 06 0.25 0.07 12. 5 21. 5 30 71. 5 30 0. 09 0. 25 0. 07 12. 5 18. 5 30. 69 30 0. 12 0. 25 0. 07 12. 5 13 30 39 30 0.15 0. 25 0.07 12.5 14. 5 30 41 30 0. 18 0. 25 0. 07 12. 5' 16 30v 84. 5 30. 0. 24' 0.25 0. 07 12.5. 21 30 189 1 1. 16. None 0.125 0.07 6. 5 57 30 174 1 2. 25

1 Total dehydration.

The preferred operating range of borax is from the lowest percentage giving a satisfactorily low water loss at room temperature to the amount which causes excessive loss of water at high temperatures F.). The optimum ranges of borax, i. e., the amount which gives the best re- Composition, Percent by weightoi Cement:

Cement, ASTM Type 11, Typical Modified Starch, 0.07%

'Iributyl phosphate- 25.111L/sackior 0.50% PV-A 12.5 mL/sack for 0.25% PVA A secondseries of tests for stiffening time and strength, at various temperatures, was made with a composition containing 0.12% borax and up to 50% PVA. Thesethickening time and strength tests were made at 140, and 200 F. The. Halliburton Consistometer and strength tests were made according to methods given in theAPI Code No. 32 (1st edition), Testing Cements Used. The results of these tests are given in Wells.

in TahleII below. These data show that borax' tends to improve the retarding properties of TABLE II Viscosity in Poises-Time t C Temp., Borax, PVA, 7 ompresstve F. Percent Percent gfig 0 0z15' 0z30 1:00 2:00 3:00 4:00 5100 0:00 hr. min

None None 6] '5' 5 '6' 7 7 1.8 15' 34 '1 906' 0.12 0. 25 v 5 0 I 6 0 7 7- s, 0- 35- 119150 0. 12 0. 50 0 0 o 0 '7 7' 12' 7 05 1', 030 None None 3 e 0 7 7 7; 7 0; 10' 2 257 0.12 0. 25 4 4 4 5 5 s o a 30 1: 0v 12 0. 50' 7 0 0 e 0 o 0 7 05 1,051 None None 3' '5 5 a "13 13' '12 5 48' 2 225' 0.12 0. 25 s 5 5 e 0 0. 7 s 40. 11860 0.12 0.50 7 5 5 '0 7 7 7 7- 20' 1901 None None 2' 5- s 11 12 Y 19 44. 4

0.12 0.25 4 5' '5 0 0, 7 s 5, 35 0.12 0.150 7 s 5 7 s 11 '13 5 Instead of borax, equivalent amounts of boric acid or alkali salts thereof may be used as shown by the examples listed in Table III below. Specifically, these examples are ortho-boric, metaboric and tetra-:boric acids, and the sodium and potassium salts thereof.

TABLE III Boron Compound Water-Loss at Temperggure Indicated (on N 0.

Whatman Paper), ml. in 30 min. at 100 A t EBorax p. s. i.

moun quive- Common Name Formula Percent P t R T ercen oom eme perature 150 Nnn a None None 29. 5 173. Boric Acid, (0rtho-) H3130: 0. 078 0. 12 23. 44. 5 Potassium Dihydrogen Borate KHzBOs 0. 084 0.08 17.0 47. 0 Sodium Dihydrogen Borate N aHzBOu 0. 106 0.12 13. 6 37. 6 Boric Acid, (Meta-) HBO: 0.030 0. 065 13.0 53. 5 Sodium Meta-bonito" NaBOz 0. 053 0. 12 19. 5 53. 6 Potassium Meta-borate K1302 0. 103 0. 12 19. 0 45. 0 Boric Acid, (Tetra) H2B4O 0. 0495 0.12 16.0 46. 0 odium Tetra-borate (Borax) NazB4O7 0. 120 0. 12 13. 0 39. 0 Potassium Tetra-borate KzB407 0. 102 0. 12 18. 0 49. 0

1 Based on B10: content.

Instead of tributyl phosphate, other defoaming agents may be used in similar amounts, such as N-decanol, polypropylene glycol (2025), diethylene glycol mono-laurate, 2-para-tert butyl phenoxy ethyl acetate, or para-tart amyl phenoxy ethanol.

In tests with various inorganic chemicals, it was also found that two other salts, namely sodium and potassium sulfate, are effective in lowering the water-losses of slurries made from the mixture of Portland cement plus polyvinyl alcohol (PVA). When about 0.60 to 1.10% of either of these salts, by weight of cement, is added, the water-losses at room temperature and at 150 F. are lowered by approximately 50%. With 0.5% PVA and 0.60 to 1.10% K2804 or NazSO :by weight of cement, approximately the same water loss is obtained as from a mixture containing 1% PVA with no added salts. Thus, the addition of these chemicals lowers the amount of PVA required to give cement the desired low water loss by approximately one-half. These compositions can readily be retarded at high temperatures with modified starch and the foaming tendency of PVA can be minimized by the use of small amounts (.015-12% by weight of cement) of tributyl phosor the other defoaming agents mentioned above.

Although we have disclosed herein the preferred embodiment of our invention, we intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.

We claim:

1. A cement composition comprising Portland cement, from .1 to 2% polyvinyl alcohol, from .02 to .30% of a compound selected from the group consisting of ortho-boric, meta-boric and tetra-boric acids and the sodium and potassium salts thereof, and from .015 to 0.12% of a detetra-boric acids, and the sodium and potassium salts thereof, and from .015 to .12% of tributyl phosphate, all said percentages being by weight of cement.

3. A slurry useful in cementing wells comprising essentially water, Portland cement, from .1 to 1% polyvinyl alcohol, from .06 to 24% of a compound selected from the group consisting of ortho-boric, meta-boric and tetra-boric acids and the sodium and potassium salts thereof, and from .015 to 0.12% of a defoaming agent, all said percentages being b weight of cement.

4. A cement composition comprising Portland cement, from .1 to 2% polyvinyl alcohol, from .02 to .30% of a compound selected from the group consisting of ortho-boric, meta-boric and tetra-boric acids and the sodium and potassium salts thereof, both said percentages being by weight of cement, and a defoaming agent.

5. A cement composition comprising Portland cement, from .1 to 1% polyvinyl alcohol, from .06 to 24% of a compound selected from the group consisting of ortho-boric, meta-boric and tetra-boric acids and the sodium and potassium salts thereof, both said percentages being by weight of cement, and a defoaming agent.

6. A slurry useful in cementing wells comprising essentially water, Portland cement, from .1 to 2% polyvinyl alcohol, from .02 to 30% of a compound selected from the group consisting of ortho-boric, meta-boric and tetra-boric acids and the sodium and potassium salts thereof, both said percentages being by weight of cement, and a defoaming agent.

MATTHEW J. BORIS. NORMAN C. LUDWIG.

No references cited. 

4. A CEMENT COMPOSITION COMPRISING PORTLAND CEMENT, FROM 1 TO 2% POLYVINYL ALCOHOL, FROM GROUP CONSISTING OF ORTHO-BORIC, META-BORIC AND TETRA-BORIC ACIDS AND THE SODIUM AND POTASSIUM SALTS THEREOF, BOTH SAID PERCENTAGES BEING BY WEIGHT OF CEMENT, AND A DEFOAMING AGENT. 